• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.24 no.1
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• pp.9-18
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• 2006

This paper describes a new program called GPS_QC needed to check the quality of GPS observations before post-processing so that the surveyors can be improved the precision of GPS data analysis. The GPS_QC was designed to calculate the quality control (QC) parameters such as data gaps, cycle slips, low elevation angle, inonspheric delay, multi-path effects and DOP etc, within the period of GPS observation. It can be used to read and calculate the QC parameters from RINEX files. This program gives users brief statistics, time series plots and graphs of QC parameters. The GPS_QC can simply be performed the quality checking of GPS data that was difficult for surveyors in the field. It is expected that we can be improved the precision of positioning and solved the time consuming problem of GPS observation.

• Korean Journal of Remote Sensing
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• v.24 no.6
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• pp.591-603
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• 2008

Satellite performance can be evaluated by image quality. MTF(Modulation Transfer Fuction), SNR(Signal To Noise Ratio), GSD(Ground Sample Distance) etc. are important bias parameters to analyze image quality. It is necessary to estimate quality of satellite image in design stage. In this paper, the simulating method of satellite image quality, considering design, manufacturing, and operation, is proposed. The proposed method shall be used to estimate and restore quality of satellite image.

• Korean Journal of Remote Sensing
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• v.37 no.3
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• pp.431-447
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• 2021

Recently, the use of high-resolution satellites is increasing in many areas. In order to supply useful satellite images stably, it is necessary to establish automatic precision geometric correction technic. Geometric correction is the process that corrected geometric errors of satellite imagery based on the GCP (Ground Control Point), which is correspondence point between accurate ground coordinates and image coordinates. Therefore, in the automatic geometric correction process, it is the key to acquire high-quality GCPs automatically. In this paper, we proposed iterative precision geometry correction method. we constructed an image pyramid and repeatedly performed GCP chip matching, outlier detection, and precision sensor modeling in each layer of the image pyramid. Through this method, we were able to acquire high-quality GCPs automatically. we then improved the performance of geometric correction of high-resolution satellite images. To analyze the performance of the proposed method, we used KOMPSAT-3 and 3A Level 1R 8 scenes. As a result of the experiment, the proposed method showed the geometric correction accuracy of 1.5 pixels on average and a maximum of 2 pixels.

• Journal of Korea Multimedia Society
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• v.7 no.3
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• pp.327-339
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• 2004

In this paper, we propose a new watermark algorithm for halftone images using iterative error minimizing method. In the proposed method, watermark bits are hidden at pseudo-random locations within a halftone image. To remove the distortions due to the inserted watermark bits and increase the invisibility of watermark, an iterative error minimizing technique is used. We define the halftoning error is defined as the difference between the original grayscale image and HVS-filtered printed halftone image. Then we iteratively find the pixel pattern with minimum halftoning error and displace the original pixel pattern with it. In order to be robust to geometrical modification like cropping or rotation, we insert the same watermark periodically into halftone images. Experiments using printed and scanned images show that the proposed method is a robust method to the geometrical modification and to hide the large amount of data within a halftone image without noticeable distortion.

• Journal of Broadcast Engineering
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• v.23 no.2
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• pp.227-234
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• 2018

Recently, stitching techniques are used for obtaining wide FOV, e.g., panorama contents, from normal cameras. Despite many proposed algorithms, the no objective quality evaluation method is developed, so the comparison of algorithms are performed only in subjective way. The paper proposes a 'Delaunay-triangulation based objective assessment method' for evaluating the geometric and photometric distortions of stitched or warped images. The reference and target images are segmented by Delaunay-triangulation based on matched points between two images, the average Euclidian distance is used for geometric distortion measure, and the average or histogram of PSNR for photometric measure. We shows preliminary results with several test images and stitching methods for demonstrate the benefits and application.

• Journal of Korea Society of Industrial Information Systems
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• v.27 no.3
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• pp.11-20
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• 2022

Currently, the black-white QR (Quick Response) codes have been used widely in consumer advertising fields and the study of color QR codes have received a growing demand because of much higher data encoding capacity. Color QR codes can be reproduced by the printing and scanning processes, however, these encounter colors distortion caused by insufficient lighting, low resolution of camera and geometric deformation during the capturing processes. In order to overcome these problems, this paper proposes an efficient decoding algorithm for color QR codes with inserted patterns, which are dealt with conventional studies. These are evaluated in view of the recognition rate under different noise conditions, for example, Gaussian noises/blurring and geometric deformation. Experimental results demonstrate that the color QR codes with simple pattern can resist the distortion of Gaussian noises/blurrings.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.33 no.1
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• pp.11-21
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• 2015

An Ortho-image is the production of removed geometrical displacement, which is generated the aerial image distortion and the relief displacement, etc., using the DSM (Digital Surface Model). Accordingly, the resolution of raw image and the accuracy of DSM will has significant impacts on the ortho-image accuracy. Since the latest DMCII250 aerial camera delivers the high resolution images with five centimeters Ground Sampling Distance(GSD), it expects to generate the high density point clouds and the high quality ortho-images. Therefore, this research has planned for reviewing the potentiality and accuracy of high quality ortho-image production. Following to proceed the research, DSM has been produced through the high density point cloud extracted from DMCII250 aerial image to supply of high density DSM by creation of ortho-image. The research results has been identified that images with the DSM brought out higher degrees in positional accuracy and quality of ortho-image, compared with the ortho-image, produced from the existing digital terrain map or DSM data.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.28 no.6
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• pp.587-594
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• 2010

This paper describe the optimal design of geodetic network by analytical technique based on the quality criteria of network. We described an example of geodetic network design taking into account the precision, reliability and robustness that are the main criteria of network design. The main goal of this paper is to evaluate the criteria to design the geodetic network coinciding with the criteria of high precision(error ellipse, 2DRMS, CEP), reliability(internal and external reliability) and robustness(maximum shear strain, principal strain, dilatation). The network design parameters computed in this study show that precision and reliability has not much improved by about 2% and 3%, respectively, than the observed network, while robustness has much improved by about 3, 100%. It also shown that maximum errors of precision, reliability and robustness were reduced by 5%, 7% and 16,957%, respectively.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2017.05a
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• pp.763-764
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• 2017

The use of barcodes in mobile phones has become generalized, and barcodes are widely used in security-sensitive applications, including mobile payment and personal identification. Generally, images photographed by a mobile phone generate geometric distortion due to the shooting angle, resulting in low quality images. Embedding watermark for low quality images makes it difficult to satisfy transparency. To solve such problem, this paper focuses on the technique of embedding barcode images in the image taken by mobile phone and proposes barcode watermarking for protecting mobile-based ownership. The barcode watermark embedded in the image can be used to prove ownership since it is readable by a machine such as illegal copy.

• Journal of Aerospace System Engineering
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• v.16 no.6
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• pp.18-23
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• 2022

This paper examines the electromagnetic shielding structure of ultra-high frequency (UHF) RF modules used in aircraft. Advances in electrical and electronic technologies have increased the need for electronic equipment in aircraft. High-frequency wireless devices have become integrated circuits in the form of UHF integrated circuits to support a wide range of frequencies and miniaturisation. To ensure the functionality and performance of these integrated devices in aviation, shielding is necessary to prevent unexpected electromagnetic interference, which could be detrimental to aircraft safety. A shield structure was designed to protect the RF chipset from malfunctioning, and the shielding effectiveness was improved through the application of various geometric shapes.